The invention relates to an automatic labeling apparatus of the type in which several pallets are carried by a turret. The turret is rotated to successively bring each pallet in contact with a glue roller, source of labels, and transfer cylinder to pick up a charge of glue, adhere a label to the charge of glue, and transfer the glued label to a bottle or other workpiece to be labeled. The known labeling apparatus applies labels quickly, accurately, and reliably, and is therefore widely used to label bottles or the like in medium to large quantities.
One problem in the art of labeling is the need to momentarily interrupt the picking up and delivery of labels when no bottles are presented for labeling. First, label pickup must start or stop in synchronization with the supply of bottles to be labeled. Second, when short gaps appear in the bottle feed, even a gap of just one bottle, the pickup of labels and glue should be stopped to avoid fouling the labeling machine with superfluous labels.
In known labeling machines label pickup is momentarily interrupted by shifting the label magazine radially outward from the turret to prevent the pallets from reaching the labels in the magazine. When operated at a high rate of label delivery, for example at approximately 70,000 bottles per hour, known magazines cannot be removed and returned rapidly enough to prevent the delivery of just one label. The prior art labeling machines can omit a single label only by being operated at a reduced rate of speed, because in prior machines large masses must be moved to retract and return the label magazine. Finally, in prior art machines the possible acceleration of the label magazine to retract or return it is limited by the need to avoid throwing labels from the label magazine.
Another known means for momentarily preventing the pickup and delivery of labels (shown in German Laid Open Specification No. 24 11 983) requires a movable section in the cam track for guiding the radial travel of each pallet. The movable section is oscillated to periodically press the glue covered surface of a pallet against the foremost label in the label magazine. If the pickup of a label is to be prevented, then the cam track section remains radially retracted to prevent the pallets from contacting the labels in the magazine. The drive for oscillating the pallets about their eccentric axes is separate, and the thrust of the oscillating means must be taken up by a spring when the cam track is locked in its retracted position. This known labeling apparatus, on account of the independent oscillating drive and the spring in the cam track section drive, is not adapted to momentarily interrupt and resume high speed label pickup and delivery.
Another defect in each prior machine is the need to complete the changeover to interrupt or resume labeling during a small fraction of a revolution of the turret if more than one pallet is carried on the turret.